I personally use Plumbers' Gold sealant (it's more like silicone than like Mait). On the top side of the basin, less is more. To be fair, a 'leak' in this location will merely mean the water will bypass the plug and drain away rather than drip out under the basin so a good seal is not technically required.
On the underside of the basin, think about where you need to seal and use an appropriate amount. A waste, fitted correctly, should look tidy and not have tons of sealant hanging off it. Wipe off any excess sealant.
Most plumbers seem to swear by Plumbers' Mait. I don't mind being in the minority as it's only natural that different tradesmen will have different opinions. I don't use it myself because, being non-setting, it has a tendency to run plus the fact that I have witnessed more leaky wastes that have been sealed with Mait than that have been sealed with other sealants puts me off. Plus I was taught there can be issues caused by the oils in the Mait affecting certain plastics. That said, if more wastes are sealed with Mait than with just rubber washers or with silicone, the number of failures alone is not a good way of measuring the proportion that have failed so I may be wrong to consider it unreliable.